Insecticidal method using 3-methylenedioxy-phenyl substituted rhodanines

ABSTRACT

An insecticidal method comprising contacting insects with an insecticidally effective amount of a compound having the formula   WHERE R&#39;&#39; is alkyl of not more than eight carbon atoms and R2 is selected from the group consisting of hydrogen and alkyl of not more than eight carbon atoms.

[72] Inventor:

United States Patent Brown [54] INSECTICIDAL METHOD USING 3- METHYLENEDIOXY-PHENYL SUBSTITUTED RHODANINES Joseph Patrick Brown, Llangollen, Wales {73] Assignee: Monsanto Chemicals Limited, London, England abandoned.

[52] US Cl ..424/270 [51] Int. Cl. ..A01n 9/12 [58] Field of Search ..424/270 [56] References Cited UNITED STATES PATENTS 1,961,840 6/1934 Bolton .Q ..424/270 2,743,21 l 4/1956 Bashour ..424/270 2,520,178 8/1950 Surrey ..260/306.7

OTHER PUBLICATIONS German Printed Application, Kerk, N7354lVa/451, 5/30/1956 [451 Oct. 10, 1972 Meiji Confectionary, Chem. Abstracts, 1963, Vol. 59, pp. 11500 Raval et al. Chemical Abstracts, 1962, Vol. 57, pp. 12465- 12466 Turkevich et al., Chemical Abstracts, 1954, Vol. 48 pp. 11392 Primary ExaminerAlbert T. Meyers Assistant Examiner-Dale R. Ore

Attomey-Neal E. Willis, Edward P. Grattan and John J. Henschke, Jr.

[5 7] ABSTRACT An insecticidal method comprising contacting insects with an insecticidally effective amount of a compound having the formula where R is alkyl of not more than eight carbon atoms and R is selected from the group consisting of hydrogen and alkyl of not more than eight carbon atoms.

3 Claims, No Drawings INSECTICIDAL METHOD USING 3- METHYLENEDIOXY-PHENYL SUBSTITUTED RHODANINES This application is a division of copending application Ser. No. 586,053 filed Oct. 12, 1966 and now abandoned.

This invention relates to new chemical compounds having insecticidal activity and to compositions containing such compounds.

The new compounds are rhodanine derivatives having a formula selected from the group consisting of wherein: R is selected from the group consisting of hydrocarbyl and substituted hydrocarbyl of not more than 18 carbon atoms, wherein the hydrocarbyl is selected from the group consisting of alkyl, alkenyl, aralkyl and cycloalkyl and the substituents on the hydrocarbyl are selected from the group consisting of halo, amino, cyano and lower alkoxy; R and R are selected from the group consisting of hydrogen, hydrocarbyl and substituted hydrocarbyl of not more than 18 carbon atoms, wherein the hydrocarbyl is selected from the group consisting of alkyl, alkenyl, aralkyl and cycloalkyl and the substituents on the hydrocarbyl are selected from the group consisting of halo, amino, cyano and lower alkoxy; R is selected from the group consisting of hydrogen, halogen and ZO wherein Z is selected from the group consisting of hydrocarbyl and substituted hydrocarbyl of not more of a rhodanine derivative as defined above, which comprises reacting a salt of a dithiocarbamic acid having a formula selected from the group consisting of R3 and A NHGSSH with a compound of the formula R1 M00o-( 3x wherein A, R, R, R and R are as defined above, M is selected from the group consisting of hydrogen, alkali metal, ammonia and alkyl of not more than four carbon atoms, and X is selected from the group consisting of fluorine, chlorine, bromine and iodine.

The insecticidal compositions of the invention comprise one or more rhodanine derivatives of the above formula in admixture with a diluent.

In the above formulas R, R, R and 2 as alkyl and substituted alkyl can be for example methyl, ethyl, chloromethyl, n-propyl, isopropyl, 2-cyanopropyl, nbutyl, 2-aminobutyl, sec-butyl, isobutyl, tertbutyl, amyl, hexyl, heptyl, ethoxyhexyl, octyl, nonyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl and the various homologues and isomers of alkyl having not more than 18 carbon atoms, as alkenyl and substituted alkenyl can be for example, vinyl, ally], n-butenyl-l n-butenyl-2, 3-bromobutenyl-2, n-pentenyl-2, n-hexenyl-Z, 3- methoxybutenyl-2, n-heptenyl, n-decenyl, n-dodecenyl and the various homologues and isomers of alkenyl having not more than 18 carbon atoms, as cycloalkyl and substituted cycloalkyl (three to 18 carbon atoms) can be for example cyclopentyl, cyclohexyl, 4-methoxycyclo-hexyl, monoand polyethylcyclohexyl, cycloheptyl, 3-chloro-cycloheptyl and the like, and as aralkyl and substituted aralkyl (seven to 18 carbon atoms) can be for example benzyl, p-aminophenylmethyl, phenylethyl, diphenylmethyl, p-chloro-phenylethyl and the like.

'7 The the above formulas R, R, R and Z are preferably alkyl of not more than eight carbons.

Where R represents a halogen atom, it can be chlorine, bromine, fluorine or iodine. R is preferably chlorine or bromine.

The substituent R0 is preferably in the para position relative to the position of attachment of the benzene nucleus to the nitrogen atom, and R is preferably in the meta position.

In the formula (b) abov e can be methylene, ethylene, ethylidene, propylene, B-propylidene and ethyl-ethylene. Preferably both oxygen atoms of the alkylenedioxy group OAO- are linked to the same carbon atom of the alkylene group. Especially preferred compounds are those in which A is methylene. Preferably one of the oxygen atoms of the alkylene-dioxy group OAO is linked to the carbon atom of the benzene ring in the para position. The other oxygen atom in such cases is necessarily linked to s stb si em nmsta s s tiqn- Representative examples of the new rhodanine V derivatives of the invention are: 3(4'-methoxyphenyl)-5-methyl-rhodanine; 3(4-methoxyphenyl)-S- ethylrhodanine; 3(4'-methoxyphenyl)-5-n-propylr- 3(4'-ethoxyphenyl)-5methyl-rhodanine; 3(2'5-methylrhodanine; 3(4'-ethoxy- 3chlorophenyl)-5-methylrhodanine; 3(4'-ethoxy-3'- I bromophenyl)-5-methylrhodanine; 3(4'-B- chloroethyoxyphenyl)-5methylrhodanine; 3(4'-ethoxyphenyl)-5-ethylrhodanine; propylrhodanine; 3 3 '4 '-dimethoxy-phenyl )rhodanine; 3 3 '4'-dimethoxyphenyl)-5-methylrhodanine; 3 (4 -npentyloxyphenyl)-5-methylrhodanine; 3(4'-ethoxyphenyl)-5,5-dimethylrhodanine; 3(4'-allyloxyphenyl)-5-methylrhodanine; 3(4-cyclohexyloxyphenyl)-5- methylrhodanine; 3(4'-benzyloxy-phenyl)-5-methylrhodanine; 3(4'-ethoxyphenyl)-5-methoxymethyl- 3 rhodanine; 3(4-ethoxyphenyl)-5-cyclohexylrhodanine; 3( 3 ,4 '-methylenedioxyphenyl )rhodanine;

3(3'4-methylenedioxyphenyl)-5-methylrhodanine;

3 3 4 -methylenedioxyphenyl ,5 -dimethylrhodanine; 3(3,4'-ethylidenedioxyphenyl)-5-ethylrhodanine; 3(4-cetyloxyphenyl)-5-methylrhodanine; 3(4'B-aminoet-hoxy-phenyl)-5-ethylrhodanine; 3(4'-npentyloxyphenyl)-5-hexyl-rhodanine; 3( 4-n-octyloxyphenyl)-5-methylrhodanine; 3(4-n-decyloxyphenyl)- S-ethylrhodanine; 3(4-}3-cyanopropyloxy-phenyl)-5- ethylrhodanine; 3 2 -propyloxyphenyl )-5-propylrhodanine; 3( 3 l ,4-dimethoxyphenyl)-5-n-octylrhodanine; 3 4'-B-pentenyloxyphenyl)-5-propylrhodanine; 3 (4-B-ethyl-hexyloxyphenyl )-5-methylrhodanine; 3 (4 '-methoxy-3 '-ethoxy-phenyl)-5-npropylrhodanine; 3 4-cycloheptyloxyphenyl )-5 ethylrhodanine; 3 4-chloromethoxyphenyl )-5 methylrhodanine; 3(4'-n-heptenyloxyphenyl)-5-ethylrhodanine; 3 4 ,3 -dimethoxy-phenyl)-5 -butylrhodanine; 3(4-ethoxyphenyl)-5-vinylrhodanine; 3(4'- B-aminopropoxyphenyD-S-methylrhodanine; 3(4'- methoxy-3 '-cyclohexyloxyphenyl )-5-methylrhodanine; 3(4'S-phenylethylrhodanine; 3(3',4 '-dimethoxyphenyl)-5,S-diethyl-rhodanine; 3(4'npropoxyphenyl)-5-benzylrhodanine; 3(3',4-dipropoxyphenyl)rhodanine; 3(4-methoxypheny1)-5-laurylrhodanine; 3(3',4'-B-propylidenedioxyphenyl)-5- methyl-rhodanine.

The salt of the dithiocarbamic acid that is a starting material in the process of the invention is preferably an alkali metal or ammonium salt. Where an alkali metal salt of the dithiocarbamic acid is employed, this is usually, for economic reasons, the sodium salt, but functionally other alkali metal salts, for example the lithium or potassium salts, are quite satisfactory. The ammonium salts of the dithiocarbamic acids that can be used include the substituted ammonium salts derived from, for example, primary and secondary amines, as well as the unsubstituted ammonium salts derived from ammonia itself. The last-named are often preferred, however,

For the other reactant in the process of the invention, it is preferred to use an ester or salt of the ahaloaliphatic monocarboxylic acid. Where an ester is employed, this is preferably an ester of an alcohol containing up to four carbon atoms, especially an ethyl ester. Preferred salts are the alkali metal salts, although ammonium and amine salts can also be used. The ahalogen atom is usually chlorine or bromine, and the number of carbon atoms and their arrangement in the ester is, of course, determined by the atoms or groups R and R required in the product.

The reaction between the salt of the dithiocarbamic acid and the a-haloaliphatic monocarboxylic acid or its ester or salt occurs readily at ordinary temperatures, for example in the range to 25C., although the process can be conducted at lower or higher temperatures, for example from 0 to 50 C., if desired.

In practice, the reactants are usually brought together in a liquid medium. This can conveniently be water or a mixture of water and an inert, watermiscible organic solvent, for instance a lower alkanol, a ketone, or dioxan. For example, a solution of an ester in a water miscible organic solvent, or a solution in water of a salt athe B-haloaliphatic monocarboxylic acid can be added to a solution or suspension of the salt of the dithiocarbamic acid in water.

An insecticidal composition of the invention can be liquid or solid, and a liquid composition can be a solution, suspension or emulsion. Often a surface active agent is present to stabilize the composition or to facilitate its application.

A composition can contain a new rhodanine derivative as the only active ingredient, or one or more other compounds having insecticidal properties can be present.

A solution of a rhodanine derivative is one in an organic solvent, for example an ester, for instance butyl acetate, a ketone, for instance methyl isobutyl ketone, a petroleum fraction, for instance white spirit, an aromatic hydrocarbon, for instance xylene or solvent naphtha, a halogenated hydrocarbon, for instance carbon tetrachloride or perchlorethylene, or some other solvent, for instance isopropyl ether or dioxan.

Such a solution can be formulated for use as an aerosol by mixing with a liquid having a boiling point below ambient temperature at atmospheric pressure for example dichlorodifluoromethane.

Where a solution contains a surface active agent, this is selected according to its solubility in the solvent but it can in general be cationic, anionic or non-ionic, anionic and non-ionic materials being generally preferred. Examples of anionic surface active agents are soaps, and the alkali metal salts, particularly the sodium salts, of long-chain alkylbenzene sulphonic acids, of long-chain alkyl sulphates and of dialkylsulphosuccinates; examples of non-ionic surface active agents are ethers and esters of polyethylene glycols, for instance the polyoxyethylene derivatives of alkylphenols and of the fatty acid mono-esters of sorbitan.

Insecticidal compositions that are suspensions can be simple ones of a rhodanine derivative in finely-divided form in an aqueous medium, stabilized if necessary by the presence of a surface active agent, for instance an anionic or nonionic agent as exemplified above.

An insecticidal composition that is an'emulsion can be obtained by emulsifying a solution of a rhodanine derivative in a suitable organic solvent, generally one that is water-immiscible, with water in the presence of a surface active agent. Where the solution already contains a surface active agent as described above, an emulsion can be formed simply by mixing with water under conditions of suitable agitation. Alternatively the surface active agent can be dissolved in the water and the solution of the rhodanine derivative added subsequently.

In compositions which are solids, the rhodanine derivative is generally present in finely-divided form and the diluent is an inert powder, for instance kieselguhr, calcium carbonate, diatomaceous earth or talc. Such a solid composition may also contain a surface active agent to facilitate its application.

The rhodanine derivatives may also be incorporated in media such as paints, varnishes and polishes.

The concentration of the rhodanine derivative in a composition of the invention can vary considerably provided the required dosage (that is a lethal or toxic amount) is supplied to the pests or their environment. Where the composition is a liquid, the concentration of the active ingredient can, for example, be from 0.001 to 10 percent by weight. For a solid composition, the lower limit of concentration is generally somewhat higher, for example 0.1 percent by weight. Concentrates in which the concentration of the rhodanine derivative may be, for example, from 10 to 50 percent by weight, and which are intended for dilution before use, are a convenient form in which the insecticides can be supplied to the user.

The invention is illustrated by the following Examples.

EXAMPLE 1 This Example describes the production of the new compound 3(4'ethoxyphenyl)-5-methylrhodanine.

Ammonium N(4-ethoxyphenyl)dithiocarbamate,

required as a starting material for the production of the rhodanine derivative, was first obtained as follows: 6 cc. of carbon disulfide were added over a period of 15 minutes to a stirred mixture of 13.7 grams of pphenetidine, 50 cc. of ethanol and 10 cc. of concentrated ammonium hydroxide. On cooling, ammonium N(4-ethoxyphenyl) dithiocarbamate crystallized from the reaction mixture and was filtered off, washed with ethanol and dried at room temperature.

The ammonium salt thus obtained was suspended in 35 cc. of water and to the stirred suspension was added a solution of 8.9 cc. of ethyl a-chloropropionate in 55 cc. of ethanol. Stirring was continued for 6 hours, after standing for a further 40 hours, 150 cc. of water were added, thereby precipitating 11.8 grams of 3(4'-ethoxyphenyl)-5-methylrhodanine in a slightly impure form having a melting point of l34l42 C. The product was obtained as yellow needles having a melting point of l47-l 5 1C., by crystallization from ethanol. (Found: C, 53.8; H, 5.1; N, 5.4; S, 23.6. C I-1 N 8; requires C, 53.4; H, 4.9; N, 5.3; S,24.0 percent).

EXAMPLE 2 This Example describes the production of 3(4" ethoxy-phenyl)--ethylrhodanine.

A suspension of ammonium N(4-ethoxyphenyl)dithiocarbamate was prepared by stirring a mixture of 7 cc. of concentrated ammonium hydroxide, 13.7 grams of p-phenetidine, 9 cc. of carbon disulfide and 25 cc. of ethanol for 2 hours at 0C. To the suspension there was then gradually added a solution of sodium abromobutyrate obtained from 16.7 grams of abromobutyric acid, 4 grams of sodium hydroxide and 30 cc. of water.

After standing overnight, the reaction mixture was acidified to pH 3 by the addition of dilute hydrochloric acid, and was then warmed to 65C. for 2 hours. After cooling, 27.1 grams of slightly impure 3(4'-ethoxyphenyl)-5-ethylrhodanine having a melting point of 98- 1 00C. were collected by filtration. Two recrystallizations from ethanol raised the melting point to l05l06 C. (Found: C, 55.4; H, 6.4; N, 4.7; S, 20.8. C H NO S requires; C, 55.6; H, 6.1; N, 4.5; S, 20.7 percent).

EXAMPLE 3 3(4'-Ethoxyphenyl)-5-n-propylrhodanine was obtained from ammonium N(4-ethoxyphenyl)dithiocarbamate and sodium a-bromovalerate by essentially the same procedure as that described in the previous Example using l/l0 molar quantities of reactants. The yield of the initial product was 27.5 grams, and its melting point was l02 C. This was raised to l05-l 06 C. by recrystallizing twice from ethanol. (Found: C,57.0; H,6.l; N,4.9; S,2l.1. C, H -,NO S requires C,56.9; H,5.8; N,4.7; 8,2 l .7 percent).

EXAMPLE 4 This Example describes the production of 3(4'- ethoxy-phenyl)-5,S-dimethylrhodanine.

A solution of sodium' a-bromoisobutyrate, obtained from 16.7 grams of a-bromoisobutyric acid, 4 grams of sodium hydroxide and 30 cc. of water, was I added gradually to a stirred suspension of ammonium N(4- ethoxyphenyl)dithiocarbamate, itself obtained by stirring a mixture of 7cc. of concentrated ammonium hydroxide, 13.7 grams of p-phenetidine, 9 cc. of carbon disulfide and 25 cc. of ethanol for 2 hours.

After standing overnight, the reaction mixture was acidified to pH 3 by the addition of dilute hydrochloric acid, and was then warmed at 65 C. for 2 hours. The main product, which was collected by filtration after cooling, was N,N-bis(4-ethoxyphenyl)thiourea. On standing, the mother liquors deposited a further crop of crystals having a melting point of l20122 C., which were identified as the required 3(4-ethoxyphenyl)-5 ,5- dimethylrhodanine. The melting point was raised to 122-l25 C. on recrystallization from ethanol. (Found: C,55.1; H,5.5; N,5.2; S,23.0. C H NO S requires C,55.5; H,5.4; N,5.0; S,22.8 percent).

EXAMPLE 5 This Example describes the production of 3(4'-n-butoxyphenyl)-5-methylrhodanine.

A solution of ammonium N(4-n-butoxyphenyl)dithio-carbamate was prepared by shaking a mixture of 16.5 grams of 4-n-butoxyaniline, 10 cc. of concentrated ammonia, 6 cc. of carbon disulfide and 30 cc. of ethanol for 2 hours and then allowing to stand at 05 C. overnight. -methylrhodanine.

A half portion of this solution was then treated with a solution of 6.5 cc. of ethyl a-bromopropionate in 30 cc. of ethanol. Crystalline material precipitated almost immediately, and after some hours standing, the weight collected by filtration was 5.6 grams. The organic constituent of this material was identified as N,N'-bis(4-rlbutoxyphenyl)thiourea. On further standing, the mother liquors from the filtration deposited a further crop of crystals weighing 1.4 grams. The melting point of these crystals was 8789 C, and analysis indicated that they were the required 3(4'-n-butoxyphenyl)-5- methylrhodamine. (Found: C,57.2; H, 5.7; N, 4.8; S, 21.4; C H NO S requires C,56.9; H, 5.8; N,4.7; S, 21.6 percent).

EXAMPLE 6 This Example describes the production of 3(4-pentyl-oxyphenyl)-5-methylrhodanine.

A mixture of 9 grams of 4-pentoxyaniline, 4cc. of carbon disulfide, 20 cc. of ethanol and 4 cc. of concentrated ammonium hydroxide was stirred at 0C. for 2 hours. Then 7 cc. of ethyl a-bromopropionate were added to the solution thus obtained, and the reaction mixture was allowed to stand overnight. On filtering, 2.6 grams of a solid mixture of ammonium bromide and N,N' bis(4-pentyloxyphenyl) thiourea were separated.

On further standing, the mother liquors deposited two further crops of crystals weighing respectively 2.2 grams and 2.3 grams. Recrystallization of the former from ethanol gave 1.1 gramsof 3(4-pentyloxyphenyl)- S-methylrhodanine having a melting point of 8l83 C. (Found: C,58.1;H,6.4; N,4.7; S,20.8. C H NO S requires C,58.3; H,6.l; N,4.5; S,20.7 percent). Recrystallization of the second crop from ethanol gave 1.6 grams of slightly less pure 3(4-pentyloxyphenyl)-5- methylrhodanine having a melting point of 72-80 C.

EXAMPLE 7 This Example describes the production of 3(4- ethoxy3 '-chlorophenyl )--methylrhodanine.

A solution of 1.65 cc. of ethyl a-bromopropionate in 18.6 cc. of ethanol was added to a stirred suspension of 3.1 grams of ammonium N(4-ethoxy-3-chlorophenyl)dithiocarbamate in 12.4 cc. of water. (The ammonium salt was first obtained in an analogous manner to the ammonium N(4-ethoxyphenyl) dithiocarbamate described in Example 1).

Next day, 31 cc. of water were added, and the residual solid, which weighed 2.5 grams, was filtered off. 3(4'-Ethoxy-3'-chlorophenyl) rhodanine having a melting point of 171-l72 C. was obtained by two successive crystallizations from ethanol. (Found: C, 48.1; H, 4.1; N, 4.4; S, 20.5; C1, 11.6; C H ClNO S requires C, 47.8; H, 4.3; N, 4.6; S, 21.2; C1, 11.8 percent).

EXAMPLE 8 This Example describes the production of 3(3', 4'- dimethoxyphenyl)rhodanine.

A mixture of 15.3 grams of 3,4-dimethoxyaniline, 50 cc. of ethanol, 10 cc. of concentrated ammonium hydroxide solution and 6 cc. of carbon disulfide was stirred for 1 hour at 0 C. and was then allowed to stand for a further hour at the same temperature. Ammonium N( 3 ,4-dimethoxyphenyl)dithio-carbamate crystallized out and was collected by filtration and dried.

A solution of 5.5 cc. of ethyl chloroacetate in 30 cc. of ethanol was added to a stirred suspension of 11.7 grams of the above ammonium salt in 50 cc. of water at room temperature. The product which separated was filtered off after 1 hour, boiled with cc. of ethanol, cooled, and again filtered, leaving a small ethanol-insoluble residue. The ethanol extract was combined with the mother liquor from the first filtration, and this solution was then diluted with 150 C of water. Solid material contaminated with tar which separated during several days standing was collected by filtration. Stirring with fresh ethanol left 1 gram of an off-white solid having a melting point of 209-210 C., and crystallization of the solid from a large volume of ethanol gave 3(3'4'-dimethoxyphenyl) rhodanine, melting point 215216 C. (Found: C, 49.3; H, 3.6; N, 5.8; S, 22.6. C H NO S, requires C, 49.9; H, 4.1; N, 5.2; S, 23.8 percent).

EXAMPLE 9 This Example describes the production of 3(3',4'- dimethoxyphenyl)-5-methylrhodanine.

A solution of 6.5 cc. of ethyl a-bromopropionate in 30 cc. of ethanol was added to a stirred suspension of 11.7 grams of ammonium N(3,4-dimethoxyphenyl)dithiocarbamate (prepared as described in Example 8) in 50 cc. of water. Essentially the same procedure as that described in Example 8 was followed in isolating the product. The solid obtained after stirring with fresh ethanol weighed 4.5 grams and had a melting point of -157 C. Crystallization from a large volume of ethanol raised the melting point to l62 C. (Found: C, 51.0; H, 4.6; N, 5.1; S, 22.3. C H NO S, requires C, 50.9; H, 4.6; N, 4.9; S, 22.6%).

EXAMPLE 10 This Example describes the production of (4'-npropoxyphenyl)-5-methylrhodanine.

A mixture of 15.1 Grams of p-n-propoxyaniline, 9 cc. of carbon disulfide and 25 cc. of ethanol were stirred for 2 hours at 0 C. A solution made from 15.3 grams of a-bromo-propionic acid, 4 grams of sodium hydroxide and 30 cc. of water was added at 0 C. Next day the reaction mixture was acidified to pH 3 with hydrochloric acid and heated to 60-70 C. for 2 hours. After cooling, 38.1 grams of the crude product, which had a melting point of 1 l21 14 C, were filtered off and recrystallized from 320 cc. of ethanol, yielding 21 grams of 3(4-n-propoxyphenyl)-5-methylrhodanine in the form of pale yellow needles having a melting point of 124-126 C.

Analysis of the product gave C, 56.3 percent; H, 5.4 percent, N, 5.6 percent; C H NO S required C, 55.5

percent; H, 5.3 percent, N, 5.0 percent.

EXAMPLE 1 1 This Example describes the production of 3(4'-isopropoxyphenyl)-5-methylrhodanine.

The method described in Example 10 was used with the substitution of p-isopropoxyaniline for p-propoxyaniline.

The yield of crude product was 28.7 grams with a melting point of 9597 C. This gave 24 grams of a purified product with a melting point of l03-105 C. upon recrystallization.

Analysis of the purified product gave C, 55.5 percent; H, 5.5 percent; N, 4.8 percent; c,,H,,No,s, requires C, 55.5 percent; H, 5.3 percent; N, 5.0 percent.

EXAMPLE 12 This Example describes the production of 3(4'-nhexyloxyphenyl)-5-methylrhodanine.

The method as described in Example 10 was used with the substitution of 19.3 grams of p-n-hexyloxyaniline for the p-n-propoxyaniline.

The yield was 28.7 grams of the crude product which had a melting point of 9394 C. Recrystallization gave 20 grams of a purified product with a melting point of 1 1 l1 13 C.

Analysis of the purified product gave C, 60.4 percent; H, 6.7 percent; N, 4.0 percent; C H NO S requires C, 59.5 percent; H, 6.5 percent; N, 4.3 percent.

EXAMPLE 13 This Example describes the production of 3(4'- methoxyphenyl)-5-methylrhodanine.

The method as described in Example was used, with 12.3 grams of p-anisidine substituted for the p-npropoxyaniline.

The yield of crude product was 24.4 grams and from this 16 grams of a purified product with a melting point of l 35137 C. were obtained by recrystallization.

Analysis of the purified product gave C, 52.6 percent; H, 4.2 percent; N, 5.2 percent; C11H11NO2S2 requires C, 52.2 percent; H, 4.4 percent; N, 5.5 percent.

EXAMPLE 14 This Example describes the production of 3(4'- methoxyphenyl)-5-ethylrhodanine.

The method was basically that described in Example 10 using as starting materials 12.3 grams of p-anisidine and 16 grams of a-bromobutyric acid, yielding 16.3 grams of a crude product having a melting point of 64-65 C. This yielded 9 grams of a purified product having a melting point of 9596 C.

Analysis of the final product gave C, 53.8 percent, H, 4.7 percent; N, 5.1 percent; S, 23.8 percent; C H NO- S requires C, 53.9 percent; H, 4.9 percent; N, 5.3 percent; S, 24.0 percent.

EXAMPLE 15 This Example describes the production of 3(4'- methoxyphenyl)-5-n-propylrhodanine.

The method was basically that described in Example 10 using as starting materials 12.3 grams of p-anisidine and 18 grams of a-bromovaleric acid. The yield of crude product, (melting point 73-95 C) was 21.5 grams, and this in turn gave 14 grams of a purified product having a melting point of 9597 C. on

recrystallization from 70 cc. of ethanol. The further purified sample had a melting point of 9698 C.

Analysis gave C, 55.5 percent; H, 5.3 percent; N, 5.0 percent; 5.22.8 percent; C H NO S requires C, 55.5 percent; H, 5.3 percent; N, 5.0 percent; S, 22.6 percent.

EXAMPLE 16 This Example Describes the production of 3(3,4'- methylenedioxyphenyl)-5-methylrhodanine.

The method described in Example 10 was used, with the modification that 13.7 grams of 3,4-methylenedioxy-aniline in 50 cc. of methanol were used in place of pn-propoxyaniline in ethanol.

A yield of 15.9 grams of a crude product with a melting point of 162C. was obtained. When this was slurried with hot ethanol and cooled, 13.7 grams of a purified product have a melting point of 169-170 C. resulted. An analytical sample recrystallized from ethanol had the form of irregular cream prisms with a melting point of 170-17l C.

Analysis of this sample gave C, 49.0 percent; H, 3.2 percent; N, 5.2 percent; CuHgNOaSg requires C, 49.4 percent; H, 3.3 percent; N,5.2 percent.

EXAMPLE 17 This Example describes the production of 3-(3'4'- methylenedioxyphenyl)-5,S-dimethylrhodanine.

The method was basically that described in Example 10 using as starting materials 13.7 grams of 3,4- methylene-dioxyaniline and 16.7 grams of 2-bromoisobutyric acid. A crude yield of 13 grams was obtained which when boiled with 9 0 cc. of ethanol gave 4.2 grams of a purified product with a melting point of l50-l53 C. A further sample had a melting point of l54155 C.

Analysis of this product gave C, 50.9 percent; H, 4.0 percent; N, 5.1 percent; C H NO S requires C, 51.2 percent; H, 3.9 percent; N, 5 .0 percent.

EXAMPLE 18 This Example describes the production of 3(4'-npropoxyphenyl)-5-ethylrhodanine.

The method was basically that described in Example 10 using 16.7 grams of a-bromobutyric acid in place of the a-bromopropionic acid. The crude product was boiled with cc. of ethanol and cooled, giving 20.5 grams of a yellowish solid with a melting point of ll7l80 C. A further recrystallized sample of this product had the same melting point.

Analysis of the compound obtained gave C, 56.8 percent; H, 5.7 percent; N, 4.9 percent; C H NO S requires C, 56.8 percent; H, 5.8 percent; N, 4.7 percent.

The method used to assess the insecticidal activity of test compounds was as follows.

A 0.05 cc. portion of a 1 percent by weight solution of the compound in acetone was added to 50 .cc. of distilled water contained in a clean 25 X 200 mm. rimless culture tube. The tube was then stoppered with an acetone-washed rubber stopper and shaken vigorously to ensure complete mixing. Then 25 early instar yellow fever mosquito larvae (Aedes aegypti) were introduced into the tube. After 24 hours at room temperature, mortality observations on the larvae were taken. In certain instances the test was repeated at lower concentration of the test compound.

The results obtained on certain of the compounds described in the above Examples are shown in the following table:

Compound Mortality/Concentrations of test compound p.p.m.

3( 4'-Ethoxyphenyl)-5-methylrl1odanine 100/ 1 0 3(4'-Ethoxyphenyl)-5-ethylrhodanine 100/ 10 /2 3(4-Ethoxyphenyl)-5-n-propylrhodanine 10 70/2 3(4-Pentyloxyphenyl)-5-rnethylrhodanine 90/10 3(4'-Ethoxy-3-chlorophenyl)-5- methylrhodanine 100/10 In addition 3(4'-ethoxyphenyl)-5 ,5 -dimethylr- 1. An insecticidal method comprising contacting insects with an insecticidally effective amount of a compound having the formula 

2. The method of claim 1 wherein the compound is 3-(3'',4''-methylenedioxyphenyl)-5-methylrhodanine.
 3. The method of claim 1 wherein the compound is 3-(3'',4''-methylenedioxyphenyl)-5,5-dimethylrhodanine. 